I recently installed the plugin Query Monitor to check a few things on a site and whilst I've not been getting any debug.log errors about this, the plugin has identified deprecated PHP in these files:-
Error: Required parameter $lineno follows optional parameter $template
Line 55 in /cred-frontend-editor/application/controllers/notification-manager/queue.php
Line 23 in /types/vendor/toolset/toolset-common/lib/Twig/src/Node/IncludeNode.php
Line 26 in /types/vendor/toolset/toolset-common/lib/Twig/src/Node/Expression/BlockReferenceExpression.php
Error: Overriding function "__" that is already registered is deprecated since version 1.30 and won't be possible anymore in 2.0.
Line 35 in /types/vendor/toolset/toolset-common/lib/Twig/src/Extension/StagingExtension.php
It is a relatively minor round of fixes left-over from the last set of updates, so I would only expect it to take a few weeks overall, but I don't know more specifically than that.
In the meantime, the issue you reported has no impact on the functionality of your site.