I adore Xiaomi's build quality (especially Redmi 4x's metal case and liked the haptics on 11 lite 5g), they are the only cheap devices with decent specs (good SDM CPUs, IR-reciever, now discontinued sdcard slots, bootloader unlocking (for LineageOS with decent privacy (and DivestOS when it still existed)), decent durability and modularity (I ocasionaly repair phones).
**But of course this is just too good to be true, so let's just start with the drawbacks: **
My first personal experience with Xiaomi was the mi 11 lite 5G, which I got as a Christmas gift in 2021. It was the best phone I ever had (both on paper and my subjective perception). Well, let's just say, that perception changed not much after the waranty; first I started experiencing random reboots and after a few months the serious issues started appearing (random connectivity problems). I tried to reflash it and it had no effect. Later all the issues started to rapidly escalate: WiFi now only works if the phone is in warm climate and it resets every couple of minutes (so it's practically useless - so I rob it for parts). Later I inherited my dad's Redmi 4x (don't worry, he isn't dead, just upgraded) and it's also starting to have this issue (after 8 years not 2). I have also seen this problem on many Xiaomis from my friends.
So in conclusion: Xiaomi purchases are a gamble. (at least if you keep a phone for a long time). But they are still the only decent low-midrange phone brand (I even recommended a Poco to my cousin)
Problem explanation: I think the problem is mostly caused by heat (from the SOC and/or the enviroment) which causes the connections on the CPU to deform and slowly lose conectivity, making the device's core functions slowly deteriorate and Xiaomi didn't fix this problem for years, as they probably don't care.
Solution (probably repairshop): edit: this is aparently bullshit
The solution to this problem is CPU reballing (a process, where you remove the CPU from the motherboard and replace it's solder. This is not an amateur job, it requires professional tools (your grandpa's old soldering iron won't do).
And of course: I would be happy if anyone would recommend a comparable brand (with at least pricing and custom roms).
lick my kitten?