It is a geeky pun, 1e100 is scientific notation for 1 followed by a hundred zeroes. This number is called a googol, which is similar sounding to google.
Others have answered your question. I would like to add that when you want to "dismantle" the URL, there is a practice in cyber security called URL Defanging. Protocols are escaped, such that http becomes hxxp. Other significant symbols that are :// becomes [://] and . becomes [.]
Combining these, your URL becomes:
hxxp[://]bom07s30-in-x03[.]1e100[.]net/
Which will be safer for others to navigate. It will take an extra effort to revert it back to the functional URL.
Tools like CyberChef can perform this action if you seek a more streamlined solution.
From mozilla. I'm guessing that the links were hosted/owned/etc. by google. When your system resumed it only partially loaded the sponsored links and you were left with the text of the url.
Your system is fine security wise, but privacy wise pinging google servers everytime you open a new tab is not ideal. This type of stuff is why I use Librewolf. Of course it's up to you how much it bothers you. You can disable alot in vanilla firefox too.
Sponsored links: Mozilla gets money for AD links showing up below the search url on the new tabs page. If you do not disable them (they are on by default).