Today I re-read your "SSD" guide (
https://easylinuxtipsproject.blogspot.com/p/ssd.html#ID6) and stumbled upon a command to verify that periodic TRIM is working:
journalctl | grep fstrim.service
On my system with Mint 19.3 and NVMe SSD it only lists a couple of failures from half a year ago. After some googling + experimenting I was able to see recent fstrim logs with another command: