Most likely a problem with the LED backlights.
LED light issues are relatively common in entry-level and budget TVs and, smart or not, Polaroid is very-much a budget brand. This is the brand that hit the headlines about 10 years ago. ASDA bought a pile of them to sell at £50 lower than the competition on Black Friday. It caused scenes of a feeding frenzy.
I would think twice about throwing any more money at the TV. However, buying a new budget TV - particularly the cheap LG and Samsung models - is to repeat the same mistake. Anything where you're at the low end of the bell curve for TVs in a particular size is usually cheap but poor value once you look past the razzle-dazzle of the size for the price and the apps. The cost-cutting in manufacturing is so savage it's the equivalent of a starving man eating himself.
Reading the reviews from sites such as rtings.com and AVForums.com then you begin to realise that there are no super-cheap bargain TVs. They're all heavily compromised by the cost-cutting. You're definitely getting what you pay for:
* big screen but not bright, and pointless having HDR
* poor video processing that makes SD channel picture quality a mess
* lots of streaming apps but no real horsepower to back up the operation. They're sluggish and destined to become unusable after they're updated a few times.
I could go on but you should have the picture by now.
If it was a toss-up between throwing say £350 at a new 50"-55" and looking at alternatives then I would seriously consider a good second-hand set or upping the budget significantly.
Most people would run a mile rather than consider a second-hand TV. I don't blame them. Most of what you'll see in the local classifieds is complete crap. It's other people's low-end TVs bought cheap and sold cheap because they just 'upgraded' to the next size bigger in the same kind of cheap crap. I'd give them a miss too. That's why you don't buy from those sort of sites.
You go to where the quality is. You go to an enthusiast forum; a place where owners have done the research on what was best to buy at the time and so what they're selling was at the top of its game when new. You buy quality but at a much lower price.
This one stood out to me in the TV classifieds at AVForums:
https://www.avforums.com/threads/sony-55-kd-55xg9505-2020-model.2416497/
The reasons are simple. It was a great TV when selling new at around £1100-£1200. It was an outstanding bargain when the last stocks were sold at £899. Seriously, there was nothing to touch it from any of the other manufacturers at under £1000. The closest you'd have got to the features would have been an LG OLED at £1200, and the Sony is way brighter.
In comparison to other LED TVs the Sony wiped the floor with them. The nearest equivalent from Samsung at the time was over £1500! That's what you had to pay to match this Sony with its 100Hz panel with full array local dimming (FALD) and full 10-bit colour-
boy are you in for a treat! - and superb colour rendition, outstanding motion- and video processing, superbly low gaming lag, HDMI 2.0 inputs, eARC and on and on and on. If you were being very picky then you could point to the fact that the Sony doesn't support HDR10+ were the Samsung did. To that I'd reply that the Sony has Dolby Vision whereas the Samsung doesn't. That's arguably more important because its the premium HDR format and more widely supported.
The Sony isn't perfect - like all high contrast VA panel TVs you need to sit more or less opposite it for the best results. This is not a TV for sitting off at the side. For that you need a TV with an IPS panel, but the blacks won't look anything like as deep and there'll be some panel glow when you watch in dimmed light. The colour also goes a bit weird at the wider viewing angles the IPS panels support.
IPS vs VA panel
If you're just looking for a cheap fix then there are a few 1080p plasmas for sale under £150. Some even as low as £50. There's a
Pioneer LX5090 50" at that price. This is a TV that predates all the Smart TV shenanigans - plug in an Amazon Fire TV stick and you'll be ahead of 90% of the Smart TVs on sale in the UK today. The bad news doesn't stop there; There's no ARC (it's optical out if you have a sound bar or surround system) and I'm not even sure there's a HD Tuner so access to the HD channels from Freeview or Freesat would need to come from a PVR. That's obviously not an issue if you have Sky or Virgin. They eat more power than a modern LED TV Too. What you will get though is one of the best 1080p TVs you could ever own.
AVForums.com TV reviews:
https://www.avforums.com/hub/tvs.8/reviews/
rtings.com TV reviews:
https://www.rtings.com/tv/reviews
rtings review of the X950G US equivalent to the UK model XG9505:
https://www.rtings.com/tv/reviews/sony/x950g
VA versus IPS panel:
https://www.rtings.com/tv/learn/ips...el usually has,color gamut, or color accuracy.
Pioneer 50" Plasma LX5090:
https://www.avforums.com/threads/pioneer-pdp-lx5090-with-wall-mount-isf-calibrated.2406303/
Pioneer LX5090 review:
https://www.whathifi.com/pioneer/pdp-lx5090/review
