If you sync your notes to icloud you can bulk export to flat text files via https://privacy.apple.com/ https://privacy.apple.com/ > "request a copy of your data

If you sync your notes to icloud you can bulk export to flat text files via https://privacy.apple.com/ https://privacy.apple.com/ > "request a copy of your data" I've never experienced data loss due to icloud sync YMMV