In short, the compilation stops after 1/7 and the error log shows the same message as in the Stackexchange discussion. The compiler works normally if I rename/remove the file /vendor/magento/module-quote-graph-ql/Model/Cart/SetShippingAddressOnCart.php, but is this file deprecated and not needed anymore from 2.3.3 onwards?
And what about the rest of the files listed by G.G. in the same topic, are they also useless in the versions 2.3.3 and newer?
If they are deprecated, is there any programmatical way to find and delete all the old/deprecated files left behind by newer versions of Magento?
This Magento has been originally installed with Installatron and it's kept up-to-date with it also.