PHP Fatal error: Allowed memory size of 268435456 bytes exhausted

Hi, my website is running on Grav since maybe January 2019. I had not checked it for a few months and when I did a week ago It did not open. Admin panel didn’t open too.
So I checked the log file in the folder and it showed a lot of
PHP Fatal error: Allowed memory size of 268435456 bytes exhausted
And it seems that they started to appear in the end of April. I haven’t upgraded or changed anything at that time (or at any time actually).
The errors seems to come from these places:
www.xxxxxxxxxx.com/cache/compiled/files/f3bcfba0517b26bc924c6501b9bac91f.yaml.php on line 1
www.xxxxxxxxxx.com/vendor/filp/whoops/src/Whoops/Util/SystemFacade.php on line 18

www.xxxxxxxxxx.com/cache/compiled/files/f3bcfba0517b26bc924c6501b9bac91f.yaml.php on line 1
www.xxxxxxxxxx.com/vendor/monolog/monolog/src/Monolog/Formatter/LineFormatter.php on line 1

There are some others here and there like:
www.xxxxxxxxxx.com/vendor/rockettheme/toolbox/File/src/File.php on line 256
www.xxxxxxxxxx.com/vendor/filp/whoops/src/Whoops/Run.php on line 378

I don’t remember which version of Grav I’m using (and I don’t know which file to check for it), but it is from somewhere in 2018. It’s running on PHP 7.2.

I will be very glad if somebody knows how to solve this problem.