Json5 error with SimpleCart price field

I have a very strange error with SimpleCart. When I enter a price of 1000 or more then the productlist goes empty in the backend. Until 999.99 there’s no problem.

I then have to manually adjust or delete the record in the mysql database to make the list back visible.

In the Modx error log I get the error “…core/model/modx/modprocessor.class.php : 268) Processor failed creating output array due to JSON error 5”

Any idea?

Latest version of SimpleCart (2.8.0) and Modx 2.8.3. PHP-version 7.4.

As SimpleCart is a commercial extra from modmore, maybe try contacting them directly or use the dedicated forum.