After the upgrade, I am unable to open and edit .md files from the dashboard

am using Docker to set up Nextcloud and recently upgraded from Nextcloud 26 to Nextcloud 27, then to 28, and finally to 29. I found that in Nextcloud 26, I could directly click on .md files from the dashboard to enter the editing screen. However, after upgrading, starting from Nextcloud 27, I can no longer click to edit; instead, it directly downloads the file. (I can still click on the file in File Explorer to edit it.)
How can I resolve this issue?

Please edit your post and fill out the support template. There is specific information requested there necessary to troubleshoot your situation. The browser inspector section in particular, but the others too.

And also check Admin settings->Overview for any warnings or errors please.