When (in 2017) the words “has been given that mark-room” appeared in RRS 18.2(d), I didn't like it right away, sorry.
Rob was kind to provided us some of the background story of the origins here on the forum in the following threads:
Unfortunately, I think there is still confusion as you as we can see from the links above & this topic-thread here: https://www.racingrulesofsailing.org/posts/812-under-new-rules-last-new-sentence-in-18-1-back-from-j-standley-post-last-aug-12th
Finally from the new The Case Book - see screenshot below. I don't think the change in 2021 has made the issue any clearer.
I think it would be better to remove this sentence from the rule or аt least change it as suggested earlier in Submission138-18 (https://www.sailing.org/tools/documents/MINRRFinal-%5B24580%5D.pdf) - " Rule 18 no longer applies between boats when mark-room has been given and the mark no longer influences the course of the boat entitled to mark-room"