First I'm surprised you needed to replace the battery so soon. You really need to monitor your battery more aggressively. Apple did have an extended warranty program for bad batteries in the 2017 systems [https://www.wired.com/story/apple-macbook-pro-recall/|June 27, 2018: Apple offers free battery replacements for faulty 13-inch Fn MacBook Pros].
Apple has a few other recall issues in this series. If you can get your self to an Apple Store or authorized service center I would as free is better than $$
Getting back to your issue I would install his gem of an app: [https://www.coconut-flavour.com/coconutbattery/|CoconutBattery] it will allow you to monitor your battery health. Post a snapshot of the apps window so we can see [guide|21499]
Also why did you re-do your systems thermal paste? Is your system overheating?