I was in the same boat. I switched to https://logseq.com/ + Google Drive. Markdown based so there's no issue with being locked in at least.
- Joplin (Nextcloud sync)
- org-mode (Nextcloud sync)
finally to Logseq (org format, not md) and Nextcloud sync. It feels like I found a solid note taking / life organising / knowledge management solution for me now.
As soon as mobile is working as well I am set for a long time.