Email Deliverability Issues with Instantly: Seeking Expert Advice

Hi everyone, a question about email deliverability. I am using Instantly for Email marketing. After a few weeks of warming up in Instatly, I launched a campaign for my client and we found that the emails were getting spammed on the recipients' Outlook inboxes. (I also use Outlook mailboxes to send emails). I tried sending some test emails directly from Outlook and Instantly, and it turned out that the emails only went to spam when sent from Instatly. Also, I did a “Deliverability Check” in Instantly and it said that this IP was marked as spam. (screen atttached) Then I tried checking it with https://0spam.org/check?ip=40.107.237.119 and it said it was marked as spam because of an email with the subject line, “free qualified calls.... no, really.” I didn't send any emails with that subject line, nor were there any warm up emails with that subject line (I checked). I don't really understand if it's really my mailbox IP “40.107.237.119” or if it's an instantly send from this IP and it's spammed If you know anything about this, please share your thoughts. (Instantly support gives very generic answers that don't help solve the problem) If you know how to fix this and avoid this problem in the future, it would be greatly appreciated.