The security update has caused problems with calculated question types already used in exams and other mathematical question types in the test activity in languages with special characters that do not correspond to the English ASCII alphabet.

This is a bug that should be fixed in the core without compromising security.

In future, the core question types should be tested before upgrades, as errors in the core question types can have a significant impact on examinations. Here is a collection of special rules for calculated tasks that complicate the creation of exam questions:
https://docs.moodle.org/405/de/Fragetyp_Berechnet#Variablen_und_zugeh%C3%B6rige_Zahlenbereiche

Requirement:
a) The use of special characters in mathematical tasks should be generally usable. It should be possible to use European/German decimal separator characters depending on the language set.
c) There is probably a bug with the units in calculated questions. When the units are entered, the variables on the next page cannot be recalculated.
d) There is probably a bug with calculated questions, if no decimal places are entered for variables, these cannot be recalculated.