iPhone xs max 5 years usage random restart after changing battery

i have been using my iphone xs max since 2019, everything worked perfectly until the past two years my battery capacity dropped to under 80%.

Since my phone would discharge super fast uder cold wether and the lightning charging port is not working well (I tried with different newly bought charging cables, most of the times my phone wont start charging, sometimes after an overnight charge the battery drop to almost dead because although it's plugged in, the process wont start), i decided to replace the battery first to see if it's only the problem of the battery that rejects charging power.

I used an iphone X battery yesterday which i remember falsely bought last year because my phone wouldn't charge and it was urgent. Although it physically didnt fit quite well I managed to separate the two battery parts without damaging the flex cables, and it worked for now with charging the phone without problem. But my phone starts to randomly shut down and restarts with a few percentage battery drop.

More details about the restart:

• restart interval: random, unlike which is described by other posts (2min50sec or 2-3min). After changing battery ive exerienced 3 restarts, once after an hour or two of usage, once after prob 10 min, and once for probably less than 1min after I turn on the screen.
• recover from shut down: if i dont touch the phone after it shuts down, it won't restart directly. Only if I press some buttons does it restart. Another thing that I noticed which never happened before, is even after restart, if I don't actively start to use the phone, all the wireless connections won't automatically start. The wifi won't connect, the blue tooth and everything. I have to stay on the phone for a few seconds even after it already restarted about 15min ago.

I will try to replace it with xs max battery to see if the problem still remains, but I wonder if someone could give some insights to what could be happening, since I dont see why a battery loose connection or anything related to the battery would cause a restart.

more to the lightning port. I dont think its a loose connection, but rather a damage on the port since ive dropped my phone multiple times yet it survived (although caused some wifi connection problem which i might need to fix in the future too). Or another possiblity would be aging, since in the recent months it came noticable for me that with the port I fail to charge my phone super randomly with different cables i bought from different shops which have no problem charging my ipad. From this post i see that it could be a sensor problem starting from the iphone X model. But as said the restart is total random. I will try and replace the charging port too.

---------------------------update 30.12.2024------------------------------

after changing the charging port, the new battery is charged faster (actually at normal speed, but much faster than before), and there's no connetion problem with the charging process anymore. If there're any problems with the restart I'll report it here. If not then its most probably because of the mulfunction of the port part.