According to the link, they say:
Following a significant security incident that led to a breach affecting multiple wallets, MyCointainer has made the decision to discontinue its operations.
This means that there was a major hack that they were unable to control, which may have led to the loss of most of the assets, and thus the service is unable to continue its operations or compensate affected users.
This also coincides with the BingX exchange hack incident, but the exchange announced that the damage was minor and that those affected will be compensated, unlike MyCointainer.
I am surprised by the large number of hacking incidents. Is this due to weak protection or due to the development of hacker methods?