Like my colleague, @Luis Sequeira1, I cannot replicate the issue that you describe. On my 16" M4 Pro MBP running macOS 27.0.1, the screenshot toolbar stays where it is placed, time after time. When the placement is in the 'snapped-to' location at the bottom center of the screen or when it is positioned elsewhere by dragging it, that position is remembered for successive screenshots (I would certainly notice a different behavior because Command-Shift-5 is my usual screenshot-taking method).

Have you rebooted your Mac? If not, that's the first step. If that does not help, then see if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems.
Start up your Mac in safe mode - Apple Support
If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.
Add a user or group on Mac - Apple Support
Once the testing is complete, the new account can easily be deleted.
Delete a user or group on Mac – Apple Support
Those steps will help to isolate the problem.
If the issue occurs in safe mode and in a new user account, that does suggest it's a bug in macOS. However, the fact that others cannot reproduce the behavior suggests that if it's a bug, there are some specific dependencies.
Unexpected issues like this that appear to be bugs but cannot be reproduced by others are often traced to 3rd party extensions with compatibility issues. If you have 3rd party ‘protection’ software installed, that may be the problem. That includes:
- Cleaners (software claiming to automatically free up space)
- Optimizers (software claiming to make your Mac run faster)
- Antivirus software
- VPN software (unless provided by a school/employer to enable access to internal resources from a remote location)
Such 3rd party system ‘helpers’, ‘cleaners’ and ‘protectors’ do more harm than good. In fact, such products are completely unnecessary for macOS and the only ‘good’ (if you want to call it that) they do is to put money in the developers’ pockets. Cleaners and protectors cause compatibility issues, often after macOS updates. Commercial VPNs claim to hide your browsing activity from websites, and while that may be true those VPN providers just sell your browsing data to others. For the user, all of these types of software offer only harm…and if that is limited to harm to your bank account, then count yourself lucky. If you have installed such software, follow the developer’s instructions to completely uninstall it (note that some developers fail to provide instructions and their software installs can be pervasive, meaning the only way to truly remove it is to erase your Mac, reinstall macOS then restore your user files from a backup).
It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed.
