Disk Not Ejected Properly

I understand that you each are busy and I appreciate your time in helping me with another issue.

Now, to the new issue. My system is a Mac mini 2020, sharing files with a Mac mini 2009 under MacOS Sonoma 14.6.1 on the mini 2020 with a Seagate 500GB External HD. I repeatedly receive stacks of notices in the upper right corner of my right-hand screen that say:

Disk Not Ejected Properly

Eject "Seagate 500GB Ext HD" before disconnecting or turning it off.

I cannot stop them from appearing. Do y'all (I'm a Texan) have any ideas/suggestions? I have tried 1) disconnecting the HD and restarting and 2) clicking on the Eject button in the Finder window and restarting. Neither has worked. I have had a stack of these windows appear repeatedly and have even tried closing each of them individually by clicking on the ⨂ that appears in the notice window as soon as the cursor touches the window.

Maybe I have to eject the HD from the Finder window each time I use the system but I'd rather not have to do that.

Again I reach out to your Mac expertise to soothe my ignorance.

Thank you in advance.

[Edited by Moderator]