No, not enclosures where odd things happen. Rather, combinations of words that look strange.
The New York Times – generally a newspaper one admires – has taken to writing things like monthslong: see, for example, Mary Hui, ‘After a Dip, Hong Kong Real Estate Again Eyes the Stratosphere’ (22 March 2019).
Compounds often start off as two or more words, become hyphenated and later lose the hyphen (holder of shares, share-holder, shareholder).
This doesn’t always work, however: securityholder looks weird. So does loophole, because it suggests the pronunciation loo-fole. The hyphen keeps a helpful separation between the consonants.
Similarly, monthslong looks unnatural (can you think of any other English word with the sequence NTHSL?) and invites one to say month-slong or the more awkward mon-thslong.
The NYT may do it, but it’s best avoided. Keep the handy hyphen.