eBay Tests Increasing Auction Bid Increments For Low Priced Items
UPDATE 3-20-25
eBay community staff have confirmed this is an intentional test being conducted by the Product Team.

Some eBay users report issues with eBay auction bid increments raising the question once again - is it a glitch, a test, or an unannounced change?
The issue was reported in the Buyer section of the eBay community forum.
What's up with eBay bid increments right now?
Ok ... have I lost my mind? Did they make a change?...I'm looking at and bidding on a handful of auctions that are below $25 (should be 50c increment) and some below $5 (should be 25c increment) and they are forcing $1 increments!?!? WHATS UP MAN!?!?
...Here is a pic of trying to place a bid, note $1 increment. Some of those auctions i placed bids, you should see $1 bid increment in bid history.
The buyer provided a few listings as examples of where they are seeing this bidding issue:
https://www.ebay.com/itm/316489526831
https://www.ebay.com/itm/267184752246
https://www.ebay.com/itm/267184748861
https://www.ebay.com/itm/267184745358
They also happen to be an experienced seller, so they are very familiar with how bidding on eBay auctions usually works, as described in this eBay policy page showing lower price items having smaller increments.

Other users responded, saying they were still seeing the normal lower bid increments and suggesting to use the question mark at the bottom right of the page to pop open a window with an option to report technical issues.
I checked all 4 of the examples they provided in both FireFox and Chrome, as well as a variety of other listings across multiple other categories, and they all showed me the incorrect $1 bid increments for lower priced items.

That suggests the issue may be account specific - either a glitch only impacting certain accounts or a test or early phased rollout of unannounced changes to how bidding on eBay auctions works.
The original poster gave a great explanation of why this is an important issue, even if it may seem that the individual financial impact may be relatively small.
Some of the items I bid on last night will sell $5-$10...
Being low value items, a $3 bid ($1 increment) may win, where a $2.25 bid (25c increment) would've also won, forcing me to pay an extra 75c due to a glitch.
Because fundamentally, no matter if the glitch costs anyone any money or not, and no matter how small the difference is now.... it is a fundamental glitch that needs to be addressed by eBay.
It just so happens to be occuring on low value items. What stops this glitch from occuring on higher value items on higher increments? Fundamentally costs people more money and I direct you back to point #1 as well. What if the bid increment on a $250 item was $25 instead of $5, or a $500 item being $50 not $10.
Are you experiencing this issue with eBay auction bid increments? Let us know in the comments below!