I just got a news article (by @thatjeffsmith-oracle ) announcing SQLcl v22.1 and some of its new features.
The most interesting one (to me) is the CodeScan feature.
I believe I had mentioned my desire to have the "custom highlighting" feature enhanced for such "code sniffing" capabilities.
With that: Thank You for adding this feature.
(image from email)

I'm assuming the blog on this feature is "coming soon".
I have some questions regarding this feature that might not show up in the blog:
Which "_slow=true" programming styles are detected?
Can we modify that list?
turn certain checks on/off
create our own
Will this feature be ported to SQL Developer?
10g CBO converts (certain) loops into Bulk Collect-FORALL. Is there a way for the engine to suggest the same? (eg here is some potentially "_slow=true" code, here is a suggested improved version - but this may be a better feature for SQL Developer)
oh ..
link to the blog?
thanks,
MK