Point light backsplash is no longer working as it used to

It seems that point backsplash was once applied only to small light-emitting surfaces, but is now applied to all surfaces, even large ones.

For example, we didn't get these artefacts in old builds of Afterslime:

Point light backsplash had been removed in ed4c8c20 in favour of area light backsplash, then later reintroduced in !210 (merged)

But perhaps it was the old behaviour (disabling the backsplash for large surfaces) that was considered a bug?

More examples with the following Xonotic map: test2.map

• With NetRadiant 20220628 and backsplash:
• With current NetRadiant and the default backsplash values:
• With current NetRadiant and -backsplash 0 0