Is the -ebbe ending in the 3rd person singular of the conditional tense pronounced /ɛbe/ or /ebe/ (e.g., "sarebbe")? Are there regional differences? I hear both in https://forvo.com/word/sarebbe/.
The answer is that the standard pronunciation is with an open “e”, /ɛ/. You may see this in most large dictionaries, such as (sorry) Treccani's entry on essere. Then, there are as many variations as Italian speakers. Open/closed vowels have an enormous variation, from correct, Crusca-like pronunciation, to pronunciations that are different but with their own regularity (like, in Rome, “colònna” rather than standard “colónna”, say), to just a single sound used in all occurrences.
For doubts about classical Italian pronunciation, I suggest the not-recent, sometimes kind of old-fashioned, but mostly reliable Dizionario di ortografia e pronunzia. For doubts as the one in the question the (slightly hidden) section about “Voci e forme di pronunzia sottintesa” is precious, and in particular that on “Desinenze grammaticali”. There, with a bit of patience, you can find that the pronunciation of “-erebbe” is given as “-erèbbe” (so with an open “e”, /ɛ/), and the same for “-irebbe” and, implicitly, “sarebbe”.
A note on your transcription: “bb” is an actual geminated sound (“doppia”), with phonemic value, so it should be /ɛb:e/.
Forvo is not especially reliable, on the other hand, since it's a wiki-like website. Anybody could insert dialectal, imprecise or plain wrong recordings just for fun. So it's about as reliable as asking a random passerby how they pronounce some word, which of course may be interesting in its own right.