It seems like this 3rd party plugin "Anti-spam by CleanTalk" caused the issue.

If this plugin you did not use for other places, I would suggest you that temporarily disabled this plugin.

If you want to use this Cleantalk Antispam for the Komento extension, you can add the CleanTalk access key from the Komento setting page (screenshot: https://monosnap.com/file/zgJy6yzEgpkuCLlfoKrrYG7sNqyYB0 ), it will work without that plugin.

If you have used this "Anti-spam by CleanTalk" for other places, then you need to temporary comment out these few lines of code from this PHP file JoomlaFolder/plugins/system/cleantalkantispam/cleantalkantispam.php (you can check my attached screenshot below) and report this issue to the CleanTalk developer regarding this.