Extra spaces I can't get rid of in Excel — TRIM isn't fixing them
You wrapped the column in TRIM and the extra space is still there. TRIM only removes the regular space character — it has no effect on a non-breaking space, the invisible character web pages and some exports use instead, which looks and behaves like a space but isn't one as far as TRIM is concerned. Drop your file in below to find out which kind you actually have.
TRIM only knows about one kind of space
Excel's TRIM function is built to remove the standard space character — ASCII/Unicode code point 32, the one your spacebar types — from the start and end of text, and to collapse repeated internal spaces down to single ones. That's the entire scope of what it does. Any other whitespace-looking character is invisible to it.
The non-breaking space is the usual suspect
A non-breaking space (code point 160, CHAR(160) in a formula, often written in HTML source) looks and displays exactly like a regular space but is a distinct character, historically used to keep two words from wrapping onto separate lines. Text copied from a website, a PDF, or exported from some line-of-business systems frequently carries these instead of, or mixed in with, regular spaces — and TRIM passes right over them because they don't match code point 32.
How to confirm that's what you're dealing with
A formula like =LEN(A1)-LEN(TRIM(A1)) returning a number greater than zero after TRIM has already run is the tell — TRIM cleaned the regular spaces it could see, and something else is still adding length. =CODE(RIGHT(A1,1)) on a cell with a trailing character will return 160 rather than 32 if it's a non-breaking space.
The fix: substitute before you trim
Wrap TRIM around a SUBSTITUTE that converts every non-breaking space to a regular one first, then let TRIM do its normal cleanup: =TRIM(SUBSTITUTE(A1,CHAR(160)," ")). For a one-time cleanup across a whole column rather than a formula, Find & Replace can search for the non-breaking space too — paste one copied from a source cell into the Find box, or use a formula helper column to isolate where they are. Upload your file above and the checker will point out exactly which cells still carry non-breaking spaces after a plain TRIM.