Hello,
KLM is trying to harmonise flight codes into clearer groups.
Ireland is joining Scandinavia in the 11 / 12 zone group, making OSL and others move up on the number list.
Summer schedule starts 31st of March. On that day Hungary is leaving group 19 and is joining zone group 13. That allows to make space for extra numbers in different groups.

Note that trains are zone group 2 (+2 digits) and buses zone group 3 (+2 digits).
These are the new zone 11/12 flight numbers :
ZONE 11 /12 : IRELAND NORWAY SWEDEN FINLAND DENMARK
ORK
→ 1127 – 1131
← 1126 – 1128
DUB
→ 1135 – 1137 – 1139 – 1141 – 1143 – 1145
← 1134 – 1136 – 1138 – 1140 – 1142 – 1144
AES
→ 1157 – 1159
← 1156 – 1158
TRD
→1151 – 1153 – 1155
←1150 – 1152 – 1154
BGO
→ 1163 – 1167 – 1169 – 1171
← 1162 – 1164 – 1168 – 1170
SVG
→ 1173 – 1175 – 1177 – 1179 – 1181
← 1172 – 1174 – 1176 – 1178 – 1180
KRS
→ 1187 – 1189
← 1188 – 1184
OSL
→ 1197 – 1199 – 1201 – 1203 – 1205 – 1207
← 1196 – 1198 – 1200 – 1202 – 1204 – 1206
ARN
→ 1215 – 1219 –1223 – 1225 – 1227
← 1214 – 1216 – 1220 – 1224 -1226
GOT
→ 1229 -1231 – 1233 – 1235 – 1239
← 1228 – 1230 – 1232 – 1234 – 1236
LPI
→ 1245 1247
← 1242 1246
HEL
→ 1251 – 1253 – 1255
← 1248 – 1252 – 1254
CPH
→ 1267 – 1269 – 1271 – 1273 – 1275 – 1277 – 1279
← 1266 – 1268 – 1270 – 1272 – 1274 – 1276 – 1278
AAL
→ 1283 – 1285 – 1287 – 1289
← 1282 – 1284 – 1286 – 1288
BLL
→1291 – 1293 – 1295 – 1297 – 1299
←1290 – 1292 – 1294 – 1296 – 1298