Ok, I will demonstrate it step-by-step:
$ getnewaddress "" "legacy"
1Y83rK42gC2KHctMmzkaqB9BgZiyYZYH9
$ dumpprivkey 1Y83rK42gC2KHctMmzkaqB9BgZiyYZYH9
L2rirSQXXu3fy77BPr1gEen1SgoNuKUu89cGvEoysrPaYZyyK67f
$ generatetoaddress 1 "1Y83rK42gC2KHctMmzkaqB9BgZiyYZYH9" 1000000000
[
"0000000056d13c49bc63b0d4a121496419d74e27a5ea0986611df1dcad787150"
]
$ getblock 0000000056d13c49bc63b0d4a121496419d74e27a5ea0986611df1dcad787150
{
"hash": "0000000056d13c49bc63b0d4a121496419d74e27a5ea0986611df1dcad787150",
"confirmations": 1,
"strippedsize": 216,
"size": 216,
"weight": 864,
"height": 1,
"version": 536870912,
"versionHex": "20000000",
"merkleroot": "a2f6aa713a1cf5d7ca6bd97e214e04b65abbac11fe06594de5d32371aaba5685",
"tx": [
"a2f6aa713a1cf5d7ca6bd97e214e04b65abbac11fe06594de5d32371aaba5685"
],
"time": 1594797319,
"mediantime": 1594797319,
"nonce": 5153686,
"bits": "1d00ffff",
"difficulty": 1,
"chainwork": "0000000000000000000000000000000000000000000000000000000200020002",
"nTx": 1,
"previousblockhash": "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"
}
$ gettransaction a2f6aa713a1cf5d7ca6bd97e214e04b65abbac11fe06594de5d32371aaba5685
{
"amount": 0.00000000,
"confirmations": 1,
"generated": true,
"blockhash": "0000000056d13c49bc63b0d4a121496419d74e27a5ea0986611df1dcad787150",
"blockheight": 1,
"blockindex": 0,
"blocktime": 1594797319,
"txid": "a2f6aa713a1cf5d7ca6bd97e214e04b65abbac11fe06594de5d32371aaba5685",
"walletconflicts": [
],
"time": 1594797319,
"timereceived": 1594797324,
"bip125-replaceable": "no",
"details": [
{
"address": "1Y83rK42gC2KHctMmzkaqB9BgZiyYZYH9",
"category": "immature",
"amount": 50.00000000,
"label": "",
"vout": 0
}
],
"hex": "02000000010000000000000000000000000000000000000000000000000000000000000000ffffffff03510101ffffffff0200f2052a010000001976a91405e2c775de292850af856a685308c5de0f39d3cf88ac0000000000000000266a24aa21a9ede2f61c3f71d1defd3fa999dfa36953755c690689799962b48bebd836974e8cf900000000"
}
Edit:
generatetoaddress 1 "3FFEdtxyXkLFHoL8Gn91aXTNrxevraKnEK"
It is not legacy address. Legacy address should start with one, not three!