import re
html = """<img src="https://s...content-available-to-author-only...e.com/path/image0.jpg?lastmod=1625296911"><br>
<div><a style="background-image:url(https://s...content-available-to-author-only...e.com/path/image1.jpg?lastmod=1625296911)"</a><a style="background-image:url(https://s...content-available-to-author-only...e.com/path/image2.jpg?lastmod=1625296912)"></a><a style="background-image:url(https://s...content-available-to-author-only...e.com/path/image3.jpg?lastmod=1625296912)"></a></div>"""
images = re.findall(r'https://s2[^\s?]*(?=\?lastmod=\d)', html)
print(images)
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