Latest update:

Google Image is back online, but only method 2 works at the moment, method 1 is not working at the moment because the plugin author removed that option (but people on Github are already asking him to add it back, consider joining them)

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Also, I'd highly recommend you to send feedback to Google (under Settings -> Send Feedback) and ask them to bring back at least the basic features (e.g. sort image by resolution under "Exact matches") to hopefully make the Google Lens at least borderline usable.

In the meantime, consider Yandex and/or Tineye as alternatives.

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(Solved, I found 2 workarounds for now:

1: This browser extension (you need to re-select Google Image instead of Google Lens in the extension's options): https://github.com/dessant/search-by-image

2: Copy the following code into the link field of a bookmark/favorite item (it's called a bookmarklet):

javascript: (() => {window.open(`https://www.google.com/searchbyimage?&client=Chrome&image_url=`+location.href, "_self");})();

then when you're on an image URL, simply click on above item you created earlier and it will take you to the legacy/classic Google Image search)

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OP below:

So, in the past, you used to be able to reverse search by image and check all the available images from large to small on Google, then at some point Google forced you to only search by Google Lens (but you were still able to click on a link in the Google Lens result to go to the good old reverse image search), but a few days earlier, that option was completely removed.

Therefore, currently I no longer have any way to find the largest image with Google reverse image search, Google Lens has become completely useless at this point (there were already plenty of complaints online about this, but in the past at least we still had an option, but that option is now gone)

For now I'm using Tineye and Yandex as alternatives, Google really need to fix this issue and stop breaking a perfectly functioning product