What you have there is indeed generally called "vertical foldover" and is an early stage of vertical collapse - the TV is having problems expanding the picture out from the middle. The fact that it has not "collapsed" completely tells us the vertical IC is probably OK, and (as Princess has pointed out) most likely failure points will be supporting electrolytic capacitors (little aluminum cans) as their electrolyte dries out eventually.
Most CRTs are approaching an age (15-20+ years) where capacitor failures are likely. Many people will just recap the entire board, but usually you don't need to change all the caps. Trouble is, sometimes failing capacitors are obvious (e.g. exploded or leaking), but sometimes they look perfectly normal.
You might want to invest in an ESR (equivalent series resistance) meter, with which you can check the health of electrolytic capacitors
without removing them from the chassis. Failing caps usually develop high resistance (ESR) which the meter measures. If ESR is too high, replace.
ESR meters to look for include any made to the Bob Parker/Dick Smith/Silicon Chip design (e.g. for a classic look
https://www.altronics.com.au/p/k2574-esr-meter-kit/, or the blue Anatek one which looks different but is the same design). There are others out there on the market too. Shouldn't cost you more than about US$110 or so, maybe cheaper.
I used to have about 8 of the original Dick Smith ESR meters (kit form) in my shed, but haven't been able to find them lately. Worried they might have been thrown out accidentally.
Your vertical deflection IC is IC401, 7 pins. Looks like a long rectangle with a corner sliced off. I see a couple of electrolytics there (470uF and 100uF).