No, that is not certain. I personally have only ever observed site leakage with 1/2" IM injections into my delts, never subq regardless of needle length.
...
Fair enough, since there's little, if any, hard data. Anecdotal reports appear to favor it. Grok says this:
Injection site leakage, where a small amount of the oil-based medication (such as testosterone enanthate or cypionate) seeps out from the puncture wound after needle withdrawal, appears to be more commonly reported with subcutaneous (SQ) injections compared to intramuscular (IM) injections. This is based on user experiences from hormone replacement therapy (HRT) and testosterone replacement therapy (TRT) communities, as well as explanations tied to the injection depth and techniques used. While clinical literature rarely addresses leakage directly (focusing instead on pharmacokinetics, safety, and common side effects like pain or swelling), anecdotal evidence consistently highlights it as a minor but frequent occurrence in SQ methods.
It was not a loaded question: "When injecting oil-based testosterone esters, is injection site leakage more prevalent with intra-muscular or subcutaneous injections?"