Product attribute in shopping cart can not be changed

[derChristoph]

We are a small club and have installed your store on our website.
Unfortunately, there are strange efekte I can not explain.

For example, if I put something in the shopping cart then I can not delete it out.
it looks like it would go, but after refreshing it is back in there here times the Probelm: https://imgur.com/B0o6HWH

how can I solve this?
You are welcome to try this out live: https://schuppesser.de/shop

Please help me

System infos:
- Version 3.5.5Beta4
- Joomla!-Version 3.9.23
- OS SunOS l
- PHP 7.4.13
- MySQLi 5.6.42-log

[Jan]

Hi, see email.