MacBook Pro M1 delete key stuck

Startup in Safe mode. https://support.apple.com/en-gb/HT201262 Choose the appropriate method.

    To leave Safe Mode, choose “Restart” at the bottom.

    Quote:

     Safe mode prevents your Mac from loading certain software when it starts up, including login items, 

     system extensions not required by macOS,

     and fonts not installed by macOS. It  also does a basic check of your startup disk, 

     similar to using First Aid in Disk Utility. 

     And it deletes some system caches, including font caches and the kernel cache, 

     which will be created again automatically as needed.

Please contact AppleCare if the sep posted above didn't help.

Every Mac comes with one year of hardware repair coverage through its limited warranty 

and up to 90 days of complimentary technical support. 

• By calling 800-275-2273 (requires you to run a remote diagnostic and provide proof of purchase)

U.S. technical support: (800) APL–CARE (800–275–2273)

https://www.apple.com/support/products/mac/

Generally, any spill or drop can damage the keyboard. If you did not experience that, and have had full control over the machine for the period, check if the stickiness could be due to Apple menu -> System Preferences -> Keyboard repeat rate. AppleCare if purchased offers some accident protection. Otherwise repairs can be costly.